This invention concerns a novel liquid flow sensing apparatus and, more particularly, a sensing apparatus that is extremely sensitive to cessation of liquid flow and is adapted to be precisely calibrated.
Although the illustrative embodiment of the present invention concerns an occluded vein sensor for use in a membrane plasmapheresis system, it is to be understood that no limitation with respect to usage of the liquid flow sensing apparatus is intended except as set forth in the appended claims.
Plasmapheresis involves the separation of plasma from whole blood, the collection of the plasma and the return of the red cells to the donor. It is desirable, if not essential, that the blood flow be carefully monitored so that an occluded vein is detected. If a vein becomes occluded, it is essential that the withdrawal of blood be terminated immediately.
Precise detecting of the blood flow is therefore necessary, and it is important that the occluded vein sensing device have the ability to be calibrated precisely. It is, therefore, an object of the invention to provide a liquid flow sensing apparatus that is very sensitive to changes in liquid flow.
Another object of the present invention is to provide a liquid flow sensing apparatus that can be calibrated very accurately.
A further object of the present invention is to provide a liquid flow sensing apparatus that can be used as an occluded vein sensor.
A still further object of the present invention is to provide a liquid flow sensing apparatus that is simple in construction and efficient to manufacture.
Other objects and advantages of the present invention will become apparent as the description proceeds.